Our research is aimed at resolving the contribution of each of the four afferent visual systems to the mediation of innate visual behavior (attention, orientation, tracking, stereopsis, learned discrimination (flux, pattern), acuity and interhemispheric transfer of learned behavior in the cat. A primary aim is to find out whether learning of pattern discrimination is mediated by the same areas of the brain which are required for interhemispheric transfer of such learning. Of special interest are the several cortical areas of the extrageniculate systems and the superior colliculus. We are attempting to uncover the neural mechanism responsible for the blindness (amblyopia) which follows certain cortical lesions and the recovery of vision subsequent to lesions in the superior colliculus and its commissure. The physiological activity mediated by the tectal and posterior commissures, and their role of interhemispheric transfer is also being studied. We are using anatomical, electrophysiological and behavioral methods.